Method of making reticulated bar grating

ABSTRACT

A bar grate and the method of making the same. The bar grate includes a reticulated grate made from a unitary flat sheet and a plurality of lengthwise extending and transversely spaced bars fastened thereto within saddles formed during the making of the reticulated grate. The saddles include projecting tab portions which are folded over and retain the bars in the grate so that no additional fastening is required. The method includes the steps of forming a reticulated grate from a flat sheet to provide a plurality of lines of bar receiving saddles, each having integral therewith tab fastening means, and inserting bars into the respective lines of saddles and bending the tabs about the bars to retain the latter fastened to the reticulated grate.

iliiiied States Patent Alien 1 28, 1972 [54] METHOD OF MAKING RETICULATED 3,108,367 10/1963 Christman ..29/455 )4 BAR GRATING 3,226,905 1/ 1966 Richardson et a1. ..52/666 [72] Inventor: John W. Allen, Flossmoor, Ill. FOREIGN PATENTS OR APPLICATIONS [73] Assignee: Stanray Corporation, Chicago, 111. 127,104 6/1902 Germany ..52/662 [22] Filed: May 1970 Primary Examiner-Charlie T. Moon [21} App1.No.: 40,164

Related US. Application Data [62] Division of Ser. No. 756,684, Aug. 30, 1968,

ArtorneySabin C. Bronson [5 7] ABSTRACT A bar grate and the method of making the same The bar grate includes a reticulated grate made from a unitary flat sheet and a plurality of lengthwise extending and transversely spaced bars fastened thereto within saddles formed during the making of the reticulated grate. The saddles include projecting tab portions which are folded over and retain the bars in the grate so that no additional fastening is required.

The method includes the steps of forming a reticulated grate from a flat sheet to provide a plurality of lines of bar receiving saddles, each having integral therewith tab fastening means, and inserting bars into the respective lines of saddles and bending the tabs about the bars to retain the latter fastened to the reticulated grate.

6 Claims, 9 Drawing Figures /)'s& y 8 J g INVENTDR JOHN WA N Patented arch 28, 1972 2 Sheets-Sheet 2 INVENTOR JOHN w. ALLEN ATT 'Y.

tislrid surface. In this type of service they are subject to considerable abuse and wear. In some applications the reticulated panels have been reinforced by bars, straps and the like so as to be capable of withstanding the forces and wear imposed thereon. These bar and strap reinforcements have been applied to the panel by separate fastening means such as bolts, rivets, welding and the like. This manner of fastening the reinforcements has not been completely satisfactory because of the possible loosening of the bolts, rivets or breaking of the weld.

By the present invention it is proposed to provide a reticulated bar grate in which the fastening means is formed integral with the reticulated grate so that separate fastening means is not required.

This is accomplished generally by the provision of a reticulated grate having a series of parallel lines of longitudinally spaced saddles into which the bars are inserted and the upper ends of the saddle legs folded over to clamp the bars to the rate. g It is another object of the present invention to provide a new and novel method for making a reticulated bar grate of the foregoing type.

The methods of forming the bar grate includes the steps of cutting a plurality of parallel lines of spaced and lengthwise extending slits in a fiat rectangular sheet of material. Each of the slits is formed with fastening or attachment tab portions intermediate the ends thereof. The alternate lines of slits are longitudinally displaced relatively to each other to form transverse rows in which the spaces between the slits in the alternate lines are generally transversely aligned with the fastening tab portions in the other lines. The slit lines are not straight but scalloped with a wider scallop in the middle of each slit to form projecting tabs when the cell grating is formed. Oppositely directed bending and saddle forming means are then applied simultaneously to adjacent rows of said slits to spread said slits and bend said flat sheet on opposite sides of said slits into a cellular or reticulated panel. The forming means in each row are arranged to form a series of parallel lines of saddles between each cell including the fastening tab portions disposed in a substantially vertical plane. Bars are inserted into each line of saddles and the fastening tabs are folded thereover to retain the bars in the grate.

Referring now to the accompanying drawings forming part of this application and wherein like reference characters indicate like parts:

FIG. 1 is a plan view of a portion of a slit metal sheet prior to being reshaped and diagrammatically showing, superimposed thereon, the position of a portion of the tooling for forming the reticulated panel, in accordance with the present inventron.

FIG. 2 is a front elevational view, taken generally along the line 2-2 of FIG. I showing two transverse lines of longitudinally spaced sets of tools with the slit metal sheet disposed therebetween prior to being formed into a reticulated panel.

FIG. 3 is a view similar to FIG. 2 but showing the position of the tooling after the metal forming operation.

FIG. 3 is a cross-sectional view taken generally along the panel, showing the bars disposed in the saddles prior to the bending thereof. 1

FIG. 6 is a cross-sectional view taken generally along the line 66 of FIG. 5.

FIG. 7 is a fragmentary end elevation of the tab bending apparatus for clamping the bars within the saddles.

FIG. 8 is a cross-sectional view taken generally along the line 8-8 of FIG. 7, illustrating the manner in which the tab bending apparatus serves to simultaneously bend a plurality of rows of tabs.

FIG. 9 is a fragmentary perspective view of the completed reticulated bar grate.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

Referring now to FIG. 9 there is shown a reticulated bar grate It) made in accordance with the present invention. The reticulated bar grate 10 comprises generally a reticulated panel 11 and a plurality of longitudinally extending bars l2 fixed thereto without the use of separate fastening means. The reticulated panel H is of the honeycomb type made from a unitary flat metal sheet and includes a plurality of transversely extending rows 13a and 13b of hexagonal shaped cells or cavities lid and 15 respectively. The rows ll3a and ll3b are alternately arranged so that the diagonally extending walls 16 defining the cells 14 and 15 are common to both. As shown, the longitudinally extending cell walls ll7-18 in the row are integral with the diagonally extending walls 16 and are the legs of an inverted saddle 19 provided during the formation of the panel 11 as more fully to be described hereinafter.

The inverted saddle 19 includes a bight portion 21 integral with the side wall forming legs 17 and 18. The structure of the saddle 19 is best illustrated in FIG. 6 showing the bars 12 seated therein. Integral with the respective side wall forming legs 17 and 18, are attachment tabs 22 and 23 which are bent over the bars 12 seated within the saddles l to retain the bars 12 fixed therein. It will be noted that the attachment tabs 22 and 23 are longitudinally displaced relatively to each other so as to avoid interference and thereby permit clamping engagement about the bar 12.

The row 1311 also includes saddles 24 which are upright rather than inverted as described above in connection with row 13a. The saddles 24 each includes longitudinal side wall forming legs 26 and 27 joined at a bight 25 as shown in FIG. 6. Attachment tabs 28 and 29 are in longitudinally displaced relationship and extend from the legs 26 and 27 respectively and are bent in clamping relationship about the edges of the bars 12 seated within the saddles 24.

From the foregoing it should be readily apparent that the reticulated bar grate ill) of the present invention provides a rigid and substantially unitary structure which is not subject to breakdown by the failure of separate fastening means.

By the present invention the saddles l9 and 2d and associated attachment tabs are integrally formed from the sheet metal of which the reticulated panel 11 is made so that the possibility of separation of the bars 12 therefrom is eliminated.

It is to be noted that the upper and lower edges of the diagonally extending common walls 16 are scalloped to provide irregular surfaces which increase the friction and thereby reduce the possibility of slipping thereon when the bar grate is used as a walkway. In this connection it is also to be noted that the attachment tabs in the bent position thereof are lengthwise spaced from each other to provide an irregular surface which also decreases the slippery characteristic of the bar grate 10.

Referring now to FIGS. I and l for a description of the method of making the reticulated bar grate 10, there is shown a metal sheet 30 and the apparatus or tooling 31 which may be used in carrying out the method.

The reticulated panel 111 is made from the substantially rectangular flat sheet 30 of metal or similar material of which only a fragmentary interior portion thereof is shown. The

sheet 30 is cut to form a series of transversely spaced and parallel slits of spaced lines 32, 33, 3d and 35 which are also parallel to the side edges of the rectangular sheet (not shown).

"The upper first line of slits 32 includes slits 36 and 37 separated by an unslit portion 38. the second line of slits 33 includes slits 39 and 40, and an unslit portion 31; the third line of slits 34 includes slits 42 and 43, and unslit portion 44; and

the fourth line of slits 35 includes slits 45 and 46 and unslit portion 47. To form the hexagonal cells 14 and 15 the end sections 48 and 48a and midsection 49 of the slits and the unslit portion are of equal lengths. To facilitate the forming of the cell walls the opposite ends of the slits terminate in apertures and the midsection is separated from the end sections by spaced apertures.

It is to be noted that the slits in lines 32, 33, 34 and 35 are staggered relative to each other so that unslit portions in alternate lines 33 and 35 are disposed in transverse alignment with the midsections 49 of the slits in the lines 32 and 34. This results in forming transverse rows 13, 13a and 13b in which the unslit portions 38 and 44 in row 13a are located in lines 32 and 34 and the unslit portions 41 and 47 in row 13b lie in lines 33 and 35. This pattern of the slits is repetitive for the full area of the metal sheet 30 from which the reticulated panel 11 is formed.

it should also be noted that the transverse distance between the parallel slit lines is equal to the height or depth of the com mon walls 16 of the cells 14 and 15. in order to maintain the dimension of the cells substantially the same, the slits are of identical length and configuration.

As above described the slits each includes the left end section 48a and the right end section 48 and the midsection 49. The slit end sections 48 and 48a are each in the form of a substantially semicircular scalloped pattern to form the upper and lower scalloped edges of the walls 16. The slit midsection 49 is shaped similarly to a sine curve to form the attachment tabs 23, 24, 28 and 29 as heretofore described in connection with the reticulated bar grate 10.

For the purpose of explanation only a portion of the tools 31 which would normally be used to form the panel 11 is described and shown herein. However, it is believed that this limited number will be adequate to provide a full understanding of the mode of operation thereof because all of the other tools operate in a similar manner.

Referring now to FIGS. 1 to 4 the tooling comprises generally a plurality of rows of cell and saddle forming tools of which only two rows are shown. It is to be understood that this pattern of tooling may be repeated for the full or partial length of the metal sheet 30. This tooling in the left row is schematically shown positioned in alignment with row 13a of the slit metal sheet and right tooling row in alignment with sheet row 13b. To further facilitate the understanding of the mode of operation of the tooling for forming the panel 11, the elements of the completed panel are identified on the fiat sheet 11 by like reference characters.

The row 13a tooling includes a plurality of punches 50 mounted on a press ram 51 and plurality of bending or forming tools 52 mounted on a press bed 53 for forming the inverted saddles 19. The number of punches i) and bending tools 52 will be dependent on the number of cells 14 and saddles 19 to be formed in row 13a of the sheet 30. The row 13b tooling also includes punches 54 and bending tools 55 of identical structure to the punches 50 and tools 52 in row 13a tooling but with the punches 54 mounted on the press bed 53 and the bending tools 55 on the press ram 51.

As shown, the punches 50 and 54 are of tapering hexagonal cross section and each terminates at the free end thereof in a ridge 56 which is aligned with the slits in the slit metal sheet. The bending tools 52 and 55 are of tapered, substantially rectangular, cross section, and each terminates in a rounded end. The bending tools 52 and 55 are aligned respectively with saddle forming cavities provided between punches 50 in row 13a tooling and the punches 54 in row 13b tooling of which only the cavities 57 in row 13a tooling are shown in FIG. 4.

To form the cell walls 16 into a plane substantially normal to the plane of the flat sheet, the rows of tooling are mounted for lengthwise movement relative to each other for reasons which will be apparent hereinafter. For purpose of explanation the row 13a is shown as being fixedly mounted against lengthwise movement on the press but it is to be understood that this tooling would normally be mounted for limited lengthwise movement a lesser distance than the tooling in row 13b tooling and the remaining tooling in subsequent right hand rows as will be more fully explained hereinafter.

For purpose of illustration, the punches 54 and forming blades or tools 55 in row 1312 are shown mounted on identical parallelogram type of mounts 57 including a pair of parallel links 58-58, each being pivotally connected at one end to a tool mounting block and the other ends to the press bed or press ram. Disposed between the parallel links 58-53 is a tension spring 59 connected between the mounting blocks and the press structure. The tension springs 59 serve to maintain the punches 54 and forming tools 55 in a vertical position. The force of the tension springs 59 is overcome to position the punches 54 and forming tools 55 longitudinally toward the tools of row 13a as shown in FIG. 3 upon the application of a power force thereto. Upon release of the power force the tension spring 59 serves to return the assemblies to the position shown in FIG. 2.

Referring again to FIGS. 1 and 2, the slit metal sheet 30 is disposed in the press between the ram 51 and bed 53. The sheet is guided and positioned in the desired location by suitable guide means 60, schematically illustrated. The guide means 60 is of substantially standard construction so that a further description is not deemed necessary.

As shown in FIG. 1, the sheet is positioned so that the ridges 56 of the punches 50 in row 13a tools are each aligned with respective ones of the slits 39 and 45. The forming tools 52 are aligned with the unslit portions 38 and 39.

The second row 13b of tooling is aligned so that the ridges 56 of the bed mounted punches 54 are aligned with the slits 36 and 37 and the ram mounted forming tools 55 aligned with the unslit portions 41 and 47. The remaining transverse rows of tooling not shown would be similarly positioned over respec tive ones of the transverse rows of slits.

The press is then actuated to initiate the closing of the head and bed. As this closing occurs the ridge lines 56 of the head mounted punches 50 engage the slits 39 and 45 to spread the metal and cause lengthwise shortening of the metal sheet 30.

At the same time the bed mounted punches 54 in row 13b tooling applies an upward force causing a spreading and up ward bending of the sheets on opposite sides of the slits 37 and 43.

In this connection it is to be noted that the right end sections 48 of slits 37 and 43 are in transverse alignment with the left end section 48a of slits 40 and 46. Thus the -metal lying between transversely aligned right and left end sections of the slits is subjected to the simultaneously applied upwardly and downwardly directed forces of the punches 50 and 54 so as to be folded into conformity with the diagonal walls of the adjacent punches 50 and 54. This folding causes a contraction of the sheet longitudinally of the slits, but no contraction thereof in the lateral direction. As this contraction occurs the row 13b tooling is moved longitudinally relative to the row 13a tooling so as to offer no resistance to the contracting movement of the sheet and thereby prevent tearing at the ends of the slits into the unslit portions. The circular apertures at the ends of the slits also reduce the tearing tendency.

As the diagonal side walls are being bent the upwardly and downwardly directed forming tools 52 and 55 engage the unslit portions 38-44 and 41-47 respectively. As shown, the forming tools 52 and 54 are of lesser height than the punches 50 and 54 so that engagement with the metal sheet 30 does not occur until the metal confined between the slit midsections 49 of the row 13a slits 39 and 45 and row 13a unslit portions 38 and 44 and the slit midsections 49 of row 13b slits 37 and 43 and row 13b unslit portions 41 and 47 has been bent downwardly and upwardly respectively to an angle of about 45.

Upon further closing of the press, the forming tools 52 and 55 force the metal into cavities 57 in between the punches 50 and the forming cavities (not shown) between the punches 54. As shown in phantom, FIG. 4, the forming tools 52 and cavities 57 form the metal defining the side walls 17 into a substantially V-shaped saddle having an included angle of about 30. It is to be noted that the saddles 19 in row 13a are inverted while the saddles 24 in row 13 are upstanding.

In connection with the formation of the saddles 24 it is to be noted that the forming tools 55 also move with the punches 54 so as to be in vertical alignment during the formation thereof. Of course, the projecting tabs 23-24 and 29-28 cut in the midsections of the slits in row 13a and row 13b project integrally from the walls as shown in FIGS. 5 and 6.

The above described reticulated panel or grate 11 is then removed from the grate forming press and placed in a tab folding and squeezing die 61 mounted in a second press 62 as shown in FIGS. 7 and 8.

Prior to closing the press 62 the bars 12 are inserted in longitudinally aligned rows of the inverted saddles l9 and the upstanding saddles 24. The die 61 includes a ram or head mounted bending die 63 having a plurality of transversely spaced supports 64 to the lower edges of which there is fixed a tab bending plate 65 formed with generally V-shaped corrugations providing a forming surface 66 for folding the tabs over the bars 12 seated in the upright saddles 24. The lower die 63a includes a plurality of transverse supports 67 fixed to the press bed along the bottom edges. Fixed to the upper edge is a similarly formed tab bending plate 68 including upwardly opening generally V-shaped corrugations which provide forming surfaces 69 for folding the tabs 22 and 23 on the inverted saddles 19 over the bars 12. Rotatably mounted between adjacent ones of the supports adjacent each of the peaks of the corrugations and extending through openings 70 in the plate 68 are squeeze rollers 72 which serve to squeeze the saddles 19 and 24 against the sides of the bars 12.

In the open position as shown in phantom lines the press head and bed are spaced apart, so that upon closing the tab bending surfaces 66 of the upper die member 63 to engage the upwardly extending attachment tabs the latter will be folded to the position shown in FIG. 8 and the forming surfaces 68 on the lower die member 63a similarly folds the downwardly projecting tabs 22 and 23 about the bars 12. At the same time the squeeze rollers 7272 which are spaced to accommodate the final thickness of the two side walls and the bar therebetween, squeezes the V-shaped saddle into a substantial U-shape as the tabs are being folded about the bar. In this manner the bars are securely and firmly fastened to the reticulated grate.

Although the embodiments constructed in accordance with the present invention have been described with the requisite particularity, the disclosure is of course exemplary. Changes in details of construction, in size, configuration and arrangement of components and materials and in modes of application will be apparent to those versed in the art and may be resorted to without departing from the scope of the invention as set forth in the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. The method of forming a bar grate comprising forming a plurality of longitudinal lines of spaced and lengthwise extending slits in a sheet with each of the slits having oppositely directed transverse slit portions defining attachment tabs, arranging the slits in adjacent lines in offset relationship to each other so that the attachment tab slits are transversely aligned with the unslit portions in the adjacent lines, thereby to define transverse rows of slits including alternate slit and unslit portions, bending the portions of the sheet between the slits in alternate rows downwardly which simultaneously bends the metal between the slits upwardly in the remaining rows to open said slits and form the cells of said panel, simultaneously applying oppositely directed forming means at said unslit portion about which the metal confined between the bar attachment tab slits in adjacent lines is bent so as to form alternate rows of upright and inverted saddles, each including said attachment tabs extending therefrom, placing bars in each of the longitudinally aligned upright and inverted saddles, and bending said bar attachment tabs about said bars to clamp said bars in said saddles.

2. he invention as defined in claim 1 wherein said saddles are bent to form a substantially V-shape and said saddles are squeezed when said bars are positioned therein to firmly engage the sides of said bars.

3. The invention as defined in claim 2 wherein said squeezing occurs while said bar attachment tabs are being bent.

4. The invention as defined in claim 2 wherein said tabs extending from said inverted and upright saddles are bent simultaneously.

5. The invention as defined in claim 2 wherein said attachment tab portions are formed substantially at the midsection of each of said slits.

6. The invention as defined in claim 5 wherein said slits are bent to form polygonal cells and said saddles are formed at the longitudinal sides thereof. 

1. The method of forming a bar grate comprising forming a plurality of longitudinal lines of spaced and lengthwise extending slits in a sheet with each of the slits having oppositely directed transverse slit portions defining attachment tabs, arranging the slits in adjacent lines in offset relationship to each other so that the attachment tab slits are transversely aligned with the unslit portions in the adjacent lines, thereby to define transverse rows of slits including alternate slit and unslit portions, bending the portions of the sheet between the slits in alternate rows downwardly which simultaneously bends the metal between the slits upwardly in the remaining rows to open said slits and form the cells of said panel, simultaneously applying oppositely directed forming means at said unslit portion about which the metal confined between the bar attachment tab slits in adjacent lines is bent so as to form alternate rows of upright and inverted saddles, each including said attachment tabs extending therefrom, placing bars in each of the longitudinally aligned upright and inverted saddles, and bending said bar attachment tabs about said bars to clamp said bars in said saddles.
 2. The invention as defined in claim 1 wherein said saddles are bent to form a substantially V-shape and said saddles are squeezed when said bars are positioned therein to firmly engage the sides of said bars.
 3. The invention as defined in claim 2 wherein said squeezing occurs while said bar attachment tabs are being bent.
 4. The invention as defined in claim 2 wherein said tabs extending from said inverted and upright saddles are bent simultaneously.
 5. The invention as defined in claim 2 wherein said attachment tab portions are formed substantially at the midsection of each of said slits.
 6. The invention as defined in claim 5 wherein said slits are bent to form polygonal cells and said saddles are formed at the longitudinal sides thereof. 